+ return 0;
+}
+
+/*
+ * We would want to bypass the object transfer altogether if
+ * everything we are going to fetch already exists and connected
+ * locally.
+ *
+ * The refs we are going to fetch are in to_fetch (nr_heads in
+ * total). If running
+ *
+ * $ git-rev-list --objects to_fetch[0] to_fetch[1] ... --not --all
+ *
+ * does not error out, that means everything reachable from the
+ * refs we are going to fetch exists and is connected to some of
+ * our existing refs.
+ */
+static int quickfetch(struct ref *ref_map)
+{
+ struct child_process revlist;
+ struct ref *ref;
+ char **argv;
+ int i, err;
+
+ /*
+ * If we are deepening a shallow clone we already have these
+ * objects reachable. Running rev-list here will return with
+ * a good (0) exit status and we'll bypass the fetch that we
+ * really need to perform. Claiming failure now will ensure
+ * we perform the network exchange to deepen our history.
+ */
+ if (depth)
+ return -1;
+
+ for (i = 0, ref = ref_map; ref; ref = ref->next)
+ i++;
+ if (!i)
+ return 0;
+
+ argv = xmalloc(sizeof(*argv) * (i + 6));
+ i = 0;
+ argv[i++] = xstrdup("rev-list");
+ argv[i++] = xstrdup("--quiet");
+ argv[i++] = xstrdup("--objects");
+ for (ref = ref_map; ref; ref = ref->next)
+ argv[i++] = xstrdup(sha1_to_hex(ref->old_sha1));
+ argv[i++] = xstrdup("--not");
+ argv[i++] = xstrdup("--all");
+ argv[i++] = NULL;
+
+ memset(&revlist, 0, sizeof(revlist));
+ revlist.argv = (const char**)argv;
+ revlist.git_cmd = 1;
+ revlist.no_stdin = 1;
+ revlist.no_stdout = 1;
+ revlist.no_stderr = 1;
+ err = run_command(&revlist);
+
+ for (i = 0; argv[i]; i++)
+ free(argv[i]);
+ free(argv);
+ return err;